The present invention relates to a magnetic actuating system, and more particularly to an improved electromagnetic yoke for operating a circuit interrupting system.
Circuit protection apparatus, including circuit breakers and interrupters, may be actuated by pneumatic, hydraulic, mechanical or magnetic means. For circuit breakers, which operate to suddenly open an electrical circuit upon sensing of an overload, often a spring-charged drive is provided. However, for contactors, which open and close a circuit but are not required to break the circuit during overcurrent (e.g., short circuit) conditions, an electromagnetic operator is frequently utilized.
It will be appreciated that it is nonetheless desirable to provide a very rapid interruption of current, whereby the magnetic operator must release in a very short period of time. In order to accomplish this, a small air gap is frequently provided in the magnetic circuit in order to increase the reluctance of the circuit, even when it is closed, for instance by means of interposing a shim of nonmagnetic material, across the extending pole ends of a core to prevent intimate contact by a mating, magnetic armature piece.
Other ways of artificially increasing the reluctance of the magnetic path are known; for instance, by directing the magnetic path through an outer, non-magnetic frame; or by providing a laminated magnet core having a non-magnetic lamination which is riveted together with the other, magnetic laminations. Such a construction is shown, for example, in German Pat. No. 1,250,552.
While methods such as increasing magnetic reluctance by means of providing a non-magnetic lamination, or interposing a non-magnetic frame, have long been utilized, it is frequently difficult to provide the precise amount of increased reluctance needed to achieve the requisite magnetic properties which will allow for the rapid disengagement of the magnet armature.
It will therefore be understood that it would be highly desirable to provide a magnetic actuating system for a contactor which has readily reproduceable and highly predictable magnetic characteristics, without the need for interposing special laminations or frame figuration in the magnetic structure.
Accordingly, it is one object of the present invention to provide an improved magnetic operator for a circuit interrupter system.
Another object is to provide an electromagnetic operator which exhibits qualities associated with a structure having an air gap, but has no actual discontinuity of the core material.
Yet another object of the invention is to provide an improved core for a magnetic operator which is readily reproduced and manufactured.